In order to cope with a rapid increase in traffic in a recent mobile communication system, a demand for a small-cell base station (also called such as “micro-cell base station”, “pico-cell base station”, “femto-cell base station”, etc.), which forms a cell (radio communication area) smaller than a conventional macro-cell base station, is increasing. Since a large number of small-cell base stations are widely disposed for coping with an increase in traffic, it is expected that the small-cell base station is disposed in the conventional macro-cell base station and a heterogeneous cellular network (HetNet) of different cell-size mixed type is configured.
As a technique of reducing inter-cell interference between the macro-cell base station and the small-cell base station, an inter-cell interference control technique of controlling and adjusting a radio frame in time domain (in a unit of subframe), presupposing that the macro-cell base station and the small-cell base station are mutually synchronized in time, is known (for example, refer to Patent Literature 1 and Non-Patent Literature 1). This inter-cell interference control technique is a technique on the basis of the LTE (Long Term Evolution)—Advanced standards and is also called as “eICIC (enhanced Inter-Cell Interference Coordination)”.